1. Field of the Invention
The present invention relates to a flip-chip bonding apparatus in which a die (semiconductor chip) is inverted and bonded directly to a substrate.
2. Prior Art
Japanese Patent No. 2725701, for instance, discloses a flip-chip bonding apparatus. In this bonding apparatus, bonding is performed in the following manner:
Numerous dies disposed on a wafer sheet with the bumps (electrodes) facing upward are picked up by a vacuum suction chucking nozzle and thus held by vacuum suction. Next, while holding a die by vacuum suction, the vacuum suction chucking nozzle is rotated in the vertical direction by a die inverting device so that the die is inverted. Then, the die held by the vacuum suction chucking nozzle is received by a bonding nozzle, the bonding nozzle transfers the die to the substrate, and the die is bonded to this substrate.
This prior art does not disclose any means for recognizing the die positioned on the wafer sheet that is to be picked up by the vacuum suction chucking nozzle or a means for correcting positional deviation of the die. However, the following type of structure is generally used therefor.
A die inverting device, which has a vacuum suction chucking nozzle, and an optical recognition device, which is positioned at a fixed offset distance from the vacuum suction chucking nozzle in order to recognize the die on the wafer sheet, are mounted on a universally known XY table and wafer holder. The universally known XY table and wafer holder are respectively driven in the X and Y directions and .theta. direction. Thus, recognition functions including the distinction between a good die and a defective die and the calculation of positional deviation of a good die, etc. are performed by this optical recognition device.
With the above system, the XY table and wafer holder are driven so that an open window (through which an image of a die is taken) provided on the optical recognition device is moved to a point above the die that is to be picked up. Then, after a die is recognized and the positional deviation of the die is calculated, the XY table and the wafer holder are driven with the offset amount between the optical recognition device and the vacuum suction chucking nozzle and the positional deviation of the die added (offset movement), thus moving the vacuum suction chucking nozzle a point above the die that is to be picked up. In this way, the positional deviation of the die is eliminated. Next, the vacuum suction chucking nozzle is lowered, and the die is picked up from the wafer sheet and held by vacuum suction. Next, while holding the die by vacuum suction, the vacuum suction chucking nozzle is rotated by the die inverting device so that the die is inverted as described above. In order to recognize the die that is to be picked up next, the XY table and wafer holder are driven so that the open window of the optical recognition device is moved to a point above the die that is to be picked up.
In the above-described prior art, the die inverting device and the optical recognition device are independently installed on the XY table and wafer holder. As a result, the overall size of the bonding apparatus becomes large. Also, since the optical recognition device is moved with the offset, mechanical error tends to occur during the positioning of the optical recognition device in the X and Y directions. Moreover, it is necessary to move the open window of the optical recognition device to a point above the next die to be picked up after the die has been picked up by the vacuum suction chucking nozzle and the vacuum suction chucking nozzle has been inverted by the die inverting device. Accordingly, die recognition cannot be performed instantly, and it takes a longer production time.